Shedding light on dark DNA Most textbook definitions of evolution state that it occurs in two stages: mutation followed by natural selection. DNA mutation is a common and continuous process, and occurs completely at random.
The average adult only eats 15 grams of fiber per day. Women need 25 grams of fiber per day, and men need 38 grams per day, according to the Institute of Medicine.
Total dietary fiber intake should be 25 to 30 grams a day from food, not supplements. Currently, dietary fiber intakes among adults in the United States average about 15 grams a day. That's about half the recommended amount.